progs/trivial/tri-stencil.c

   1 /*
   2  * Copyright (c) 1991, 1992, 1993 Silicon Graphics, Inc.
   3  *
   4  * Permission to use, copy, modify, distribute, and sell this software and
   5  * its documentation for any purpose is hereby granted without fee, provided
   6  * that (i) the above copyright notices and this permission notice appear in
   7  * all copies of the software and related documentation, and (ii) the name of
   8  * Silicon Graphics may not be used in any advertising or
   9  * publicity relating to the software without the specific, prior written
  10  * permission of Silicon Graphics.
  11  *
  12  * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF
  13  * ANY KIND,
  14  * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
  15  * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
  16  *
  17  * IN NO EVENT SHALL SILICON GRAPHICS BE LIABLE FOR
  18  * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
  19  * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
  20  * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
  21  * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  22  * OF THIS SOFTWARE.
  23  */
  24
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <math.h>
  29 #include <GL/glut.h>
  30
  31
  32 static void Init(void)
  33 {
  34 }
  35
  36 static void Reshape(int width, int height)
  37 {
  38
  39     glViewport(0, 0, (GLint)width, (GLint)height);
  40
  41     glMatrixMode(GL_PROJECTION);
  42     glLoadIdentity();
  43     glOrtho(-5.0, 5.0, -5.0, 5.0, -5.0, 5.0);
  44     glMatrixMode(GL_MODELVIEW);
  45 }
  46
  47 static void Key(unsigned char key, int x, int y)
  48 {
  49
  50     switch (key) {
  51       case 27:
  52         exit(1);
  53     }
  54 }
  55
  56 static void Draw(void)
  57 {
  58    glShadeModel(GL_FLAT);
  59
  60    {
  61       glClearColor(0.0, 0.0, 0.0, 0.0);
  62       glClearStencil(0);
  63       glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
  64    }
  65
  66
  67    glStencilMask(1);
  68    glEnable(GL_STENCIL_TEST);
  69    glStencilFunc(GL_ALWAYS, 1, 1);
  70    glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
  71
  72    glColor3ub(200, 0, 0);
  73    glBegin(GL_POLYGON);
  74    glVertex3i(-4, -4, 0);
  75    glVertex3i( 4, -4, 0);
  76    glVertex3i( 0,  4, 0);
  77    glEnd();
  78
  79 #if 1
  80    glStencilFunc(GL_EQUAL, 1, 1);
  81    glStencilOp(GL_INCR, GL_KEEP, GL_DECR);
  82
  83    glColor3ub(0, 200, 0);
  84    glBegin(GL_POLYGON);
  85    glVertex3i(3, 3, 0);
  86    glVertex3i(-3, 3, 0);
  87    glVertex3i(-3, -3, 0);
  88    glVertex3i(3, -3, 0);
  89    glEnd();
  90 #endif
  91
  92 #if 0
  93    glStencilFunc(GL_EQUAL, 1, 1);
  94    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
  95
  96    glColor3ub(0, 0, 200);
  97    glBegin(GL_POLYGON);
  98    glVertex3f(2.5, 2.5, 0);
  99    glVertex3f(-2.5, 2.5, 0);
 100    glVertex3f(-2.5, -2.5, 0);
 101    glVertex3f(2.5, -2.5, 0);
 102    glEnd();
 103 #endif
 104
 105    glFlush();
 106 }
 107
 108 static GLenum Args(int argc, char **argv)
 109 {
 110     GLint i;
 111
 112
 113     for (i = 1; i < argc; i++) {
 114         if (strcmp(argv[i], "-dr") == 0) {
 115         } else {
 116             printf("%s (Bad option).\n", argv[i]);
 117             return GL_FALSE;
 118         }
 119     }
 120     return GL_TRUE;
 121 }
 122
 123 int main(int argc, char **argv)
 124 {
 125     GLenum type;
 126
 127     glutInit(&argc, argv);
 128
 129     if (Args(argc, argv) == GL_FALSE) {
 130         exit(1);
 131     }
 132
 133     glutInitWindowPosition(0, 0); glutInitWindowSize( 300, 300);
 134
 135     type = GLUT_RGB | GLUT_SINGLE | GLUT_DEPTH | GLUT_STENCIL;
 136     glutInitDisplayMode(type);
 137
 138     if (glutCreateWindow("Stencil Test") == GL_FALSE) {
 139         exit(1);
 140     }
 141
 142     Init();
 143
 144     glutReshapeFunc(Reshape);
 145     glutKeyboardFunc(Key);
 146     glutDisplayFunc(Draw);
 147     glutMainLoop();
 148         return 0;
 149 }